The present invention relates generally to sterilizers and, more particularly, to a sterilizer including a system for purging air to increase the steam content within a sterilizer chamber, and a seal which increases sealing forces with increasing sterilizer chamber pressure.
Sterilizers are widely used to sterilize articles in medical environments and typically employ a steam filled chamber for containing the articles, and rely on subjecting the articles to steam at a predetermined temperature and pressure for a preset period of time. The steam may either be provided by means of a separate steam producing chamber or by supplying water to the sterilizer chamber and heating the chamber until the water evaporates. In either case, the chamber is provided with a heater to elevate the temperature in the chamber and cause an accompanying increase in pressure such that sterilization of the articles is effected.
To ensure proper sterilization, it is desirable to replace any air in the sterilizer chamber with steam. This has been accomplished in prior art devices by applying a vacuum to the chamber to draw the air out or, in an alternative approach, a vent is opened as the chamber fills with steam to permit the air in the chamber to be displaced and pushed out of the chamber by the steam. For example, U.S. Pat. No. 3,826,612 to Black discloses an autoclave or sterilizer in which a steam generating chamber delivers steam to an autoclaving chamber wherein a temperature responsive valve is in fluid communication with the autoclaving chamber and permits air to pass out of the chamber, and which closes automatically upon an appreciable rise in the temperature as a result of steam flowing from the chamber through the valve.
In addition, table top sterilizers conventionally have doors pivoted to one side such that the door swings upon a vertical axis. In a typical use of such a sterilizer, the door is partially opened after release of pressure within the chamber, and before the articles in the chamber have cooled, to permit any moisture remaining on the articles to evaporate more quickly as the moisture content within the chamber decreases. For example, U.S. Pat. No. 5,223,229 to Brucker, and assigned to the assignee of the present invention, discloses a sterilizing apparatus having a door mounted on a vertical axis and wherein the door is automatically actuated to open a small amount when the pressure within the sterilizer chamber decreases to a predetermined level to facilitate cooling and drying of articles within the chamber.
The cooling process results in condensation and dripping of moisture in the area of the gap between the door and the chamber opening, and there is a need to reduce the amount of moisture lost in the form of condensation from the sterilizer. In addition, there is a need for an improved sterilization process which increases the amount of steam relative to the amount of air contained within the chamber during the sterilization process.